Tuning the Composition of FeCo Nanoparticle Heating Agents for Magnetically Induced Catalysis

Magnetic heating by nanoparticles has recently been successfully employed in heterogeneous catalysis. In such processes, the maximum temperature that can be reached depends on the Curie temperature ( T c ) of the heating material. Here, in order to extend the range of accessible temperatures and consequently the range of possible reactions, to those requiring high temperatures, we developed and fully characterized a series of FeCo nanoparticles containing different concentrations of cobalt, in order to tune their magnetic properties and T c . Their efficiency is compared to that of iron carbide nanoparticles, which display a lower T c . Specific absorption rate (SAR) measurements as a function of temperature, performed using a homemade pyrometer-based setup, clearly show that although the heating power of iron carbide nanoparticles is higher at room temperature it decreases more rapidly with temperature than that of iron cobalt nanoparticles, in agreement with their lower T c . In a showcase, Fe 0.5 Co 0.5 nanoparticles allow, in addition to CO 2 hydrogenation, dry reforming of propane and methane, and dehydrogenation of propane, these reactions requiring temperatures of 350 °C, 600 °C, and 700 °C, respectively. Furthermore, the use of Fe 0.5 Co 0.5 nanoparticles is less energy demanding, as it allows carrying out CO 2 hydrogenation at lower magnetic fields and at frequencies as low as 100 kHz. Dry reforming of methane and propane were carried out in the presence of a Ni nanoparticle-based catalyst, whereas dehydrogenation of propane required as a catalyst PtSn nanoparticles synthesized through an organometallic route. Fe 0.5 Co 0.5 nanoparticles can therefore be used as universal heating agents allowing reactions to be performed up to ca. 700 °C upon association with the appropriate catalyst.